Ok this might sound a bit confusing but its the answer to why you are interested in an uninteresting guy.

first from what ur saying, you dont have a boyfriend, a guyfriend that u like etc... basically - leaving the prick out for a second - u have no interest towards any guy.... women are known to enjoy caring about someone or/and liking somone, showing interest in someone, being attracted to someone (no matter what it is u find attractive). Woman love those feelings, and when u go to bed you're always thinking about that someone and dreaming/imagining going into fantasies of him saving you from evil monsters or god knows what etc etc
when all of a sudden (this happens at some stage of our lives beleive it or not) there is not one guy around u that you have interest in (apart from sexy guys u see on tv) Automatically when a woman has no guy to care about or have a crush on then this sort of becomes unusual and u start having little crushes on random guys. yup its true even pricks.
so in your situation if im right, you dont really have any interest in any guy and this prick is like a temporarily crush perhaps. no matter what dont feel forced into anything because ur feelings sometimes tricks you.
hope this made sense...